Semiconductor devices having lower and upper fins and method for fabricating the same

ABSTRACT

Provided are a semiconductor device and a method for fabricating the same. The semiconductor device includes a lower fin that protrudes from a substrate and extends in a first direction, an oxide film the lower fin, an upper fin that protrudes from the oxide film and that is spaced apart from the lower fin at a position corresponding to the lower fin, and a gate structure the upper fin that extends in a second direction to intersect the upper fin, wherein germanium (Ge) is included in a portion of the oxide film located between the lower fin and the upper fin.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 from KoreanPatent Application No. 10-2014-0084463, filed on Jul. 7, 2014 in theKorean Intellectual Property Office, the entire contents of which isincorporated by reference herein in its entirety.

BACKGROUND

Field-effect transistors are now available that exhibit high-speedoperation at low operating voltages and that have a high integrationdensity. In order to more efficiently withstand a short channel effectand provide a higher drive current at low operating voltages as comparedto a conventional field-effect transistor, there is a rising interest infin field effect transistors (FinFET) which have channels that areformed in a three-dimensional structure.

In recent years, in order to improve the performance of thesemiconductor device, there has been used a technique in which a layerincluding a stress material is formed by epitaxial growth to increasethe carrier mobility of a channel region of the semiconductor device.

SUMMARY

An aspect of the inventive concepts provides a semiconductor devicehaving a Fin On Insulator (FOI) structure which may provide improvedoperating characteristics in a FinFET device. The FOI structure may beformed, for example, using a difference in oxidation rate betweensilicon (Si) and silicon germanium (SiGe).

Another aspect of the inventive concepts provides a method forfabricating a semiconductor device having an FOI structure using adifference in oxidation rate between silicon (Si) and silicon germanium(SiGe).

However, aspects of the present inventive concept are not restricted tothe above. The above and other aspects of the inventive concepts willbecome more apparent to one of ordinary skill in the art to which theinventive concepts pertain by referencing the detailed descriptionbelow.

According to one aspect of the inventive concepts, there is provided asemiconductor device having a lower fin that protrudes upwardly from asubstrate and that extends in a first direction, an oxide film on thelower fin, an upper fin that extends in the first direction above thelower fin, the upper fin protruding upwardly from the oxide film andspaced apart from the lower fin, and a gate structure on the upper finthat extends in a second direction to intersect the upper fin, whereingermanium (Ge) is included in a portion of the oxide film that isbetween the lower fin and the upper fin.

According to another aspect of the inventive concepts, there is provideda semiconductor device that includes a substrate having a first regionand a second region, a lower fin that protrudes from the first region ofthe substrate and that extends in a first direction, a first oxide filmon the lower fin, an upper fin that extends in the first direction, thatprotrudes from the first oxide film, and that is above and spaced apartfrom the lower fin, a first gate structure on the upper fin that extendsin a second direction, a fin structure formed protruding from the secondregion of the substrate that extends in the first direction, a secondoxide film on the substrate covering at least a portion of a sidewall ofthe fin structure, and a second gate structure that extends in thesecond direction on the fin structure, wherein a material which is notincluded in the second oxide film is included in the first oxide film.

According to yet another aspect of the inventive concepts, asemiconductor device is provided that includes a first lower fin thatextends in a first direction; a second lower fin that extends in thefirst direction that is spaced apart from the first lower fin; an oxidelayer that covers sides surfaces and top surfaces of the first lower finand the second lower fin; a first upper fin on the oxide layer, thefirst upper fin extending in the first direction above the first lowerfin and spaced apart from the first lower fin; a second upper fin on theoxide layer, the second upper fin extending in the first direction abovethe second lower fin and spaced apart from the second lower fin, whereinthe oxide layer includes a first portion that is between the first lowerfin and the first upper fin that includes a first material, a secondportion that is between the second lower fin and the second upper finthat includes the first material, and a third portion that is betweenthe first portion and the second portion that does not include the firstmaterial.

According to still another aspect of the inventive concepts, there isprovided a method for fabricating a semiconductor device that includespreparing a substrate that has a fin structure that includes a firstmaterial layer and a second material layer protruding upwardlytherefrom, forming an oxide film on the substrate to cover at least aportion of the fin structure, annealing the fin structure to convert thefin structure into a lower fin and an upper fin that is spaced apartfrom the lower fin, removing a portion of the oxide film, and forming agate structure on the upper fin that intersects the upper fin.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the inventive concepts willbecome more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings, in which:

FIG. 1 is a perspective view of a semiconductor device according to afirst embodiment of the inventive concepts;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1;

FIG. 4 is a cross-sectional view of a semiconductor device according toa second embodiment of the inventive concepts;

FIG. 5 is a cross-sectional view of a semiconductor device according toa third embodiment of the inventive concepts;

FIG. 6 is a cross-sectional view of a semiconductor device according toa fourth embodiment of the inventive concepts;

FIGS. 7 and 8 are cross-sectional views of a semiconductor deviceaccording to a fifth embodiment of the inventive concepts;

FIG. 9 is a cross-sectional view of a semiconductor device according toa sixth embodiment of the inventive concepts;

FIG. 10 is a cross-sectional view of a semiconductor device according toa seventh embodiment of the inventive concepts;

FIGS. 11 to 13 are circuit and layout diagrams of a semiconductor deviceaccording to an eighth embodiment of the inventive concepts;

FIG. 14 is a flowchart illustrating a method for fabricating asemiconductor device according to one embodiment of the inventiveconcepts;

FIG. 15 is a flowchart illustrating a method for fabricating asemiconductor device according to another embodiment of the inventiveconcepts;

FIG. 16 is a flowchart illustrating a method for fabricating asemiconductor device according to still another embodiment of theinventive concepts;

FIGS. 17 to 22 are diagrams showing intermediate structures formed in amethod for fabricating a semiconductor device according to oneembodiment of the inventive concepts;

FIG. 23 is a diagram showing an intermediate structure formed in step amethod for fabricating a semiconductor device according to anotherembodiment of the inventive concepts;

FIGS. 24 to 28 are diagrams showing intermediate structures formed in amethod for fabricating a semiconductor device according to still anotherembodiment of the inventive concepts;

FIGS. 29 and 30 are diagrams showing intermediate structures formed in amethod for fabricating a semiconductor device according to still anotherembodiment of the inventive concepts;

FIG. 31 is a schematic block diagram of an electronic system including asemiconductor device according to some embodiments of the inventiveconcepts; and

FIG. 32 is a schematic block diagram for explaining an applicationexample of an electronic system including a semiconductor deviceaccording to some embodiments of the inventive concepts.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventive concepts will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsare shown. The inventive concepts may, however, be embodied in differentforms and should not be construed as limited to the embodiments setforth herein. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the inventive concepts to those skilled in the art. The samereference numbers indicate the same components throughout thespecification. In the attached figures, the thickness of layers andregions may be exaggerated for clarity.

It will also be understood that when a layer is referred to as being“on” another layer or substrate, it can be directly on the other layeror substrate, or intervening layers may also be present. In contrast,when an element is referred to as being “directly on” another element,there are no intervening elements present.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein to describe one element orfeature's relationship to another element(s) or feature(s) asillustrated in the figures. It will be understood that the spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,elements described as “below” or “beneath” other elements or featureswould then be oriented “above” the other elements or features. Thus, theexemplary term “below” can encompass both an orientation of above andbelow. The device may be otherwise oriented (rotated 90 degrees or atother orientations) and the spatially relative descriptors used hereininterpreted accordingly.

The use of the terms “a” and “an” and “the” and similar referents are tobe construed to cover both the singular and the plural, unless otherwiseindicated herein or clearly contradicted by context. The terms“comprising,” “having,” “including,” and “containing” are to beconstrued as open-ended terms (i.e., meaning “including, but not limitedto,”) unless otherwise noted.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the inventive concepts belong. It is noted that the useof any and all examples, or exemplary terms provided herein is intendedmerely to better illuminate the inventive concepts and is not alimitation on the scope of the inventive concepts unless otherwisespecified.

The inventive concepts will be described with reference to perspectiveviews, cross-sectional views, and/or plan views, in which exampleembodiments are shown. Thus, the profile of an exemplary view may bemodified according to manufacturing techniques and/or allowances. Thatis, the embodiments described herein are not intended to limit the scopeof the inventive concepts but cover all changes and modifications thatcan be caused due to a change in manufacturing process. Thus, regionsshown in the drawings are illustrated in schematic form and the shapesof the regions are presented simply by way of illustration and not as alimitation.

Hereinafter, a semiconductor device 1 according to a first embodiment ofthe inventive concepts will be described.

FIG. 1 is a perspective view of the semiconductor device 1. FIG. 2 is across-sectional view taken along line A-A of FIG. 1. FIG. 3 is across-sectional view taken along line B-B of FIG. 1.

Referring to FIGS. 1 to 3, the semiconductor device 1 includes asubstrate 100, an oxide film 110, lower fins LF1 and LF2, upper fins UF1and UF2, gate structures TR and the like.

The substrate 100 may be a rigid substrate such as a silicon substrate,a silicon on insulator (SOI) substrate, a gallium arsenide substrate, asilicon germanium substrate, a ceramic substrate, a quartz substrate, ora glass substrate for a display, or a flexible plastic substrate such aspolyimide, polyether, polycarbonate, polyethersulfone,polymethylmethacrylate, polyethylene naphthalate orpolyethyleneterephthalate substrates.

The substrate 100 may include a first region I and a second region II.The first region I and the second region II may be separated by a deviceisolation film (not shown) formed by, for example, shallow trenchisolation (STI). The first region I may be a PMOS region and the secondregion II may be an NMOS region, but inventive concepts are not limitedthereto. The first region I may be an NMOS region, and the second regionII may be a PMOS region.

The lower fins LF1 and LF2 may protrude upwardly from the substrate 100and extend in a second direction Y. The lower fins LF1 and LF2 may bepart of the substrate 100.

The oxide film 110 may be formed on the lower fins LF1 and LF2. Theoxide film 110 may be formed on the substrate 100 to cover the sidesurfaces and the upper surfaces of the lower fins LF1 and LF2. In orderto form a fin-on-insulator (FOI) structure, the oxide film 110 may beformed to cover the entire upper surfaces of the lower fins LF1 and LF2.

The oxide film 110, which may act as an insulating film, may be a HDPoxide film, a SOG oxide film, a CVD oxide film or the like, but is notlimited thereto.

The upper fins UF1 and UF2 may protrude upwardly from the oxide film 110and may be formed at positions corresponding to the lower fins LF1 andLF2 to be spaced apart from the lower fins LF1 and LF2. As shown inFIGS. 1 and 3, the upper fins UF1 and UF2 may substantially verticallyoverlap the lower fins LF1 and LF2, respectively. Since the upper finsUF1 and UF2 are formed at positions corresponding to the lower fins LF1and LF2, the upper fins UF1 and UF2 may also extend in the seconddirection Y. Further, since the upper fins UF1 and UF2 protrude upwardlyfrom the oxide film 110 and are spaced apart from the lower fins LF1 andLF2, the semiconductor device may have a fin shape having a FOIstructure.

As shown in FIGS. 1 and 3, the upper fins UF1 and UF2 may be partiallyrecessed into an upper surface of the oxide film 110.

In the semiconductor device 1, a silicon germanium (SiGe) layer may beformed between two silicon (Si) layers, and the silicon germanium (SiGe)layer may then be oxidized to form a portion of the oxide film 110.Accordingly, germanium (Ge) is included in portions a and a′ of theoxide film 110 that are located, respectively, between the lower fin LF1and the upper fin UF1 and between the lower fin LF2 and the upper finUF2.

The oxidation rate of silicon germanium (SiGe) is higher than theoxidation rate of silicon (Si). Accordingly, when the silicon germanium(SiGe) layer that is formed between the two silicon (Si) layers isannealed under oxidizing conditions, the silicon germanium (SiGe) layermay be oxidized to form an insulating film, but the silicon (Si) layermay not be oxidized.

Since the FOI structure is formed by performing such an annealingprocess, the silicon (Si) layers that form the lower fins LF1 and LF2and the upper fins UF1 and UF2 are not oxidized, while the silicongermanium (SiGe) layer is converted into the portions a and a′ of theoxide film 110 that are located between the lower fins LF1 and LF2 andthe upper fins UF1 and UF2. Accordingly, germanium (Ge) is present inthe portions a and a′ of the oxide film 110.

The gate structure TR may be formed on the upper fins UF1 and UF2. Thegate structure TR may extend in a first direction and may intersect theupper fins UF1 and UF2. The first direction may be the X direction.

The gate structure TR may include an interface film 120, a gateinsulating film 130, a work function adjusting film 140, gate metal 150,a gate spacer 160 and the like, which may be sequentially formed on theupper fins UF1 and UF2. In the semiconductor device 1, a channel may beformed on both side surfaces and upper surfaces of the upper fins UF1and UF2.

The interface film 120 may be formed on the oxide film 110 and on sidesurfaces and upper surfaces of the upper fins UF1 and UF2. The interfacefilm 120 may improve the interface between the oxide film 110 and thegate insulating film 130.

The interface film 120 may include a low-k material layer having adielectric constant k which is equal to or less than 9. For example, theinterface film 120 may be a silicon oxide film (k is about 4) or asilicon oxynitride film (k is about 4 to 8 depending upon the content ofoxygen atoms and nitrogen atoms). In other embodiments, the interfacefilm 120 may be formed of silicate, or a combination of the filmsmentioned above.

The gate insulating film 130 may be formed on the interface film 120.However, if the interface film 120 is not present, the gate insulatingfilm 130 may be formed directly on the oxide film 110 and the upper finsUF1 and UF2.

The gate insulating film 130 may include a high-k material. For example,the gate insulating film 130 may be any one selected from the groupconsisting of HfSiON, HfO₂, ZrO₂, Ta₂O₅, TiO₂, SrTiO₃, BaTiO₃ andSrTiO₃.

The gate insulating film 130 may have an appropriate thickness based onthe type of a device to be formed. For example, if the gate insulatingfilm 130 includes HfO₂, the gate insulating film 130 may have athickness of about 50 Å or less (about 5 Å to 50 Å), but is not limitedthereto.

According to some embodiments of the inventive concepts, as shown inFIG. 1, the gate insulating film 130 may extend upward along thesidewall of the gate spacer 160, which will be described later.

The work function adjusting film 140 may be formed on the gateinsulating film 130. The work function adjusting film 140 may directlycontact the gate insulating film 130. The work function adjusting film140 may also extend upward along the sidewall of the gate spacer 160.The work function adjusting film 140 is used for adjusting a workfunction.

The work function adjusting film 140 may include, for example, metalnitride. Specifically, the work function adjusting film 140 may includeat least one of Mo, Pd, Ru, Pt, TiN, WN, TaN, Ir, TaC, RuN, TiAl, TaAlC,TiAlN and MoN. The work function adjusting film 140 may be formed of asingle film including TiN, a double film including a lower TiN film andan upper TaN film, or the like, but the inventive concepts are notlimited thereto.

The gate metal 150 may be formed on the work function adjusting film140. As illustrated, the gate metal 150 may directly contact the workfunction adjusting film 140. That is, the gate metal 150 may fill aspace defined by the work function adjusting film 140. The gate metal150 may include a conductive material, for example, W or Al, but is notlimited thereto.

The gate spacer 160 may be formed on at least one side of the sidesurfaces of the gate structure TR. The gate spacer 160 may include atleast one of a nitride film, an oxynitride film and a low-k material.

Further, although the outer side surface of the gate spacer 160 isillustrated as having a curved shape, the inventive concepts are notlimited thereto. For example, the gate spacer 160 may have an I shape orL shape in further embodiments.

Further, although the gate spacer 160 is illustrated as a single layerin the drawings, it will be appreciated that the gate spacer 160 mayalternatively include a plurality of layers.

A source/drain is formed on one side of both sides of the gate structureTR. The source/drain(s) may be formed in the upper fins UF1 and UF2. Thegate spacer 160 may insulate the source/drain from the gate structureTR.

Hereinafter, semiconductor devices according to other embodiments of theinventive concepts will be described.

FIG. 4 is a cross-sectional view of a semiconductor device 2 accordingto a second embodiment of the inventive concepts. For simplicity ofdescription, a description of substantially the same parts as thoseincluded in the semiconductor device 1 will be omitted.

Referring to FIG. 4, in the semiconductor device 2, the upper surface ofa lower fin LF1′ may have a first tip portion 10, and the lower surfaceof an upper fin UF1′ may have a second tip portion 20.

After the silicon germanium (SiGe) layer is formed between the twosilicon (Si) layers, a first annealing process is performed underoxidizing conditions to oxidize the silicon germanium (SiGe) layer.

The silicon (Si) layer on the lower side of the silicon germanium (SiGe)layer is formed as the lower fin LF1′, and the silicon (Si) layer on theupper side of the silicon germanium (SiGe) layer is formed as the upperfin UF1′. The silicon germanium (SiGe) layer is oxidized to form theportions of the oxide film 110 that are between the lower fin LF1′ andthe upper fin UF1′. This result is obtained because the oxidation rateof the silicon germanium (SiGe) layer is higher than the oxidation rateof the silicon (Si) layer.

As a result of performing the first annealing process, the upper surfaceof the lower fin LF1′ may have the first tip portion 10 and the lowersurface of the upper fin UF1′ may have the second tip portion 20.

That is, each of the first tip portion 10 and the second tip portion 20is an end portion of the fin and may have a substantially pointed shape.However, the shape of the first tip portion 10 and the second tipportion 20 is not limited to the shape shown in FIG. 4, and may, forexample, have an irregular bent portion according to the processconditions.

The first annealing process may form the FOI structure in which thelower fin LF1′ and the upper fin UF1′ are completely separated by theoxidized silicon germanium (SiGe) layer.

FIG. 5 is a cross-sectional view of a semiconductor device 3 accordingto a third embodiment of the inventive concepts. For simplicity ofdescription, a description of substantially the same parts as those ofthe semiconductor device 1 will be omitted.

Referring to FIG. 5, in the semiconductor device 3, a lower fin LF1″ andan upper fin UF1″ may be made of different materials.

For example, the lower fin LF1″ may be made of silicon (Si) that is anoriginal material, and the upper fin UF1″ may include a first material30. In this case, the first material 30 may be germanium (Ge), but isnot limited thereto.

After forming the lower fin LF1″ and the upper fin UF1″ by annealing thedevice under oxidizing conditions, silicon (Si) that forms the upper finUF1″ may be removed, and an epitaxial layer may be formed using thesilicon germanium (SiGe) layer that remains below the upper fin UF1″ asa seed layer. Thus, the upper fin UF1″ may be formed as an epitaxiallayer that includes germanium (Ge).

In a PMOS region of a FinFET device, the upper fin UF1″ may be formed asan epitaxial layer that includes germanium (Ge) to provide a compressivestress to a channel region. However, the inventive concepts are notlimited thereto, and the upper fin UF1″ may be formed to include adifferent material if necessary.

FIG. 6 is a cross-sectional view of a semiconductor device 4 accordingto a fourth embodiment of the inventive concepts. For simplicity ofdescription, a description of substantially the same parts as those ofthe semiconductor device 1 will be omitted.

Referring to FIG. 6, in the semiconductor device 4, an upper fin UF1″′may include a second material layer 31 and a third material layer 32which are different materials.

The second material layer 31 and the third material layer 32 may be madeof different materials than the material of the lower fin LF1″′.

For example, the lower fin LF1″′ may be made of silicon (Si) that is anoriginal material, the second material layer 31 of the upper fin UF1″may be made of a material including germanium (Ge), and the thirdmaterial layer 32 of the upper fin UF1″ may include a III-V groupcompound semiconductor material. However, these materials are merelyexemplary, and the inventive concepts are not limited thereto.

After forming the lower fin LF1′″ and the upper fin UF1′″ by annealingthe device under oxidizing conditions, the silicon (Si) that forms theupper fin UF1″′ may be removed, and an epitaxial process may beperformed using the silicon germanium (SiGe) layer remaining below theupper fin UF1″′ as a seed layer. Thus, the upper fin UF1″′ may be formedas a first epitaxial layer that includes germanium (Ge) and as a secondepitaxial layer that includes a III-V group compound semiconductormaterial.

Accordingly, the lower fin LF1″′ may include silicon (Si), the secondmaterial layer 31 of the upper fin UF1″′ may include germanium (Ge), andthe third material layer 32 of the upper fin UF1′″ may include a III-Vgroup compound semiconductor material.

FIGS. 7 and 8 are cross-sectional views of a semiconductor device 5according to a fifth embodiment of the inventive concepts. Forsimplicity of description, a description of substantially the same partsas those of the semiconductor device 1 will be omitted.

Referring to FIGS. 7 and 8, the semiconductor device 5 includes asubstrate 100 in which a first region I and a second region II aredefined, a lower fin LF11, a first oxide film 110′, an upper fin UF11, afirst gate structure TR1, a fin structure F, a second oxide film 210, asecond gate structure TR2 and the like.

The lower fin LF11 may protrude from the first region I of the substrate100 and extend in a first direction. The lower fin LF11 may be part ofthe substrate 100.

The first oxide film 110′ may be formed on the lower fin LF11. As shownin FIG. 8, the first oxide film 110′ may be formed on the substrate 100to cover the side surfaces and the upper surface of the lower fin LF11.In order to form a FOI structure on the first region I of the substrate100, the first oxide film 110′ may cover the entire upper surface of thelower fin LF11.

The first oxide film 110′ may serve as an insulating film and may be anHDP oxide film, a SOG oxide film, a CVD oxide film or the like, but isnot limited thereto.

The upper fin UF11 may protrude from the first oxide film 110′ and maybe formed at a position corresponding to the lower fin LF11 and may bespaced apart from the lower fin LF11. Since the upper fin UF11 is formedat the position corresponding to the lower fin LF11, the upper fin UF11may also extend in the first direction. The upper fin UF11 may bevertically aligned with the lower fin LF11. The upper fin UF11 may berecessed within the first oxide film 110′.

In the semiconductor device 5, after a silicon germanium (SiGe) layer isformed between two silicon (Si) layers, the silicon germanium (SiGe)layer is oxidized to form at least a portion of the first oxide film110′. Accordingly, germanium (Ge) is included in a portion a″ of thefirst oxide film 110′ that is located between the lower fin LF 11 andthe upper fin UF 11.

When the silicon (Si) layer and the silicon germanium (SiGe) layer areoxidized by performing an annealing process one or more times underoxidizing conditions, the silicon germanium (SiGe) layer is convertedinto an oxide film that serves as an insulating film, but the silicon(Si) layer is not oxidized into an insulating film.

Since the FOI structure is formed by performing such a process, thesilicon (Si) layers are formed as the lower fin LF11 and the upper finUF11, and the silicon germanium (SiGe) layer becomes the portion a″ ofthe first oxide film 110′ that is located between the lower fin LF11 andthe upper fin UF 11. Accordingly, germanium (Ge) is present in theportion a″ of the first oxide film 110′.

The first gate structure TR1 may be formed on the upper fin UF11 in asecond direction that intersects the upper fin UF11. The first gatestructure TR1 may include an interface film 120, a gate insulating film130, a work function adjusting film 140, gate metal 150, a gate spacer160 and the like, which are sequentially formed on the upper fin UF11. Achannel may be formed on both side surfaces and an upper surface of theupper fin UF11. The interface film 120, the gate insulating film 130,the work function adjusting film 140, the gate metal 150 and the gatespacer 160 may be substantially the same as those described above withreference to FIGS. 1-2.

The fin structure F may protrude from the second region II of thesubstrate 100 and extend in the first direction. The fin structure F maybe part of the substrate 100.

The second oxide film 210 may cover the side surfaces of the finstructure F. The second oxide film 210, which serves as an insulatingfilm, may be a HDP oxide film, a SOG oxide film, a CVD oxide film or thelike, but is not limited thereto.

An upper portion of the fin structure F may be formed as an epitaxiallayer 300. The epitaxial layer 300 may be formed of a material whichprovides a compressive stress to a channel region. However, theinventive concepts are not limited thereto, and the epitaxial layer 300may be formed of a material which provides a tensile stress ifnecessary.

The gate structure TR2 may be formed on the fin structure F in adirection to intersect the fin structure F. The gate structure TR2 mayinclude an interface film 220, a gate insulating film 230, a workfunction adjusting film 240, gate metal 250, a gate spacer 260 and thelike, which are sequentially formed on the fin structure F.

The interface film 220, the gate insulating film 230, the work functionadjusting film 240, the gate metal 250 and the gate spacer 260 may besubstantially the same as the interface film 120, the gate insulatingfilm 130, the work function adjusting film 140, the gate metal 150 andthe gate spacer 160, respectively, that are described above withreference to FIGS. 1-2.

In the semiconductor device 5, the FOI structure is formed on the firstregion I of the substrate 100, and the silicon germanium (SiGe) layer isoxidized to form the portion a″ of the first oxide film 110′ that servesas an insulating film. Thus, a material included in the first oxide film110′ may be different from a material included in the second oxide film210.

That is, a material which is not included in the second oxide film 210may be included in the first oxide film 110′. This material may be, forexample, germanium (Ge).

FIG. 9 is a cross-sectional view of a semiconductor device 6 accordingto a sixth embodiment of the inventive concepts. For simplicity ofdescription, a description of substantially the same parts as those ofthe semiconductor devices 1, 5 according to the first and fifthembodiments will be omitted.

Referring to FIG. 9, in the semiconductor device 6, a lower fin LF11′and an upper fin UF11′ that are made of different materials are formedon the first region I of the substrate 100.

For example, the lower fin LF1 P may be made of silicon (Si) that is anoriginal material, and the upper fin UF11′ may be made of a materialincluding a fourth material 40. In this case, the fourth material 40 maybe germanium (Ge), but is not limited thereto.

That is, after forming the lower fin LF11′ and the upper fin UF11′ byperforming the annealing process a plurality of times, silicon (Si)forming the upper fin UF11′ may be removed, and an epitaxial process maybe performed using the silicon germanium (SiGe) layer remaining belowthe upper fin UF11′ as a seed layer. Thus, the upper fin UF11′ may beformed as an epitaxial layer that includes germanium (Ge).

For example, if the first region I is a PMOS region, the upper fin UF11′may be formed as an epitaxial layer that includes germanium (Ge) toprovide a compressive stress to a channel region.

FIG. 10 is a cross-sectional view of a semiconductor device 7 accordingto a seventh embodiment of the inventive concepts. For simplicity ofdescription, a description of substantially the same parts as those ofthe semiconductor devices 1, 5 according to the first and fifthembodiments of the inventive concepts will be omitted.

Referring to FIG. 10, in the semiconductor device 7, an upper fin UF11″may include a fifth material layer 41 and a sixth material layer 42which are made of different materials.

The fifth material layer 41 and the sixth material layer 42 may be madeof different materials than the material of the lower fin LF11″.

For example, the lower fin LF11″ may be made of silicon (Si) that is anoriginal material, the fifth material layer 41 of the upper fin UF11″may be made of a material that includes germanium (Ge), and the sixthmaterial layer 42 of the upper fin UF11″ may include a III-V groupcompound semiconductor material. However, these materials are merelyexemplary, and the inventive concepts are not limited thereto.

After forming the lower fin LF 11″ and the upper fin UF11″ by performingthe annealing process, silicon (Si) forming the upper fin UF11″ may beremoved, and an epitaxial process may be performed using the silicongermanium (SiGe) layer remaining below the upper fin UF11″ as a seedlayer. Thus, the upper fin UF11″ may be formed as an epitaxial layerincluding the III-V group compound semiconductor material.

Accordingly, the lower fin LF11″ may include silicon (Si), the fifthmaterial layer 41 of the upper fin UF11″ may include germanium (Ge), andthe sixth material layer 42 of the upper fin UF11″ may include a III-Vgroup compound semiconductor material.

FIGS. 11 to 13 are circuit and layout diagrams illustrating asemiconductor device according to an eighth embodiment of the inventiveconcepts.

FIGS. 11 and 12 are a circuit diagram and a layout diagram,respectively, of the semiconductor device according to the eighthembodiment of the inventive concepts. FIG. 13 illustrates only aplurality of fins and a plurality of gate structures in the layoutdiagram of FIG. 12. The above-described semiconductor devices accordingto embodiments of the inventive concepts may be applied to any deviceconfigured as a general logical device using a fin type transistor, buta SRAM is illustrated as an example in FIGS. 11 to 13.

Referring to FIGS. 12 and 13, the semiconductor device according to theeighth embodiment of the inventive concepts includes a first active finF10 that is formed in a first direction, and a second gate line 352 thatis formed in a second direction to intersect the first active fin F10.

An oxide film is formed below the first active fin F10. A first material(e.g., germanium) may be included in a region N of this oxide film wherethe first active fin F10 and the second gate line 352 do not overlapeach other, and may not be included in the oxide film in a region Owhere the second gate line 352 and first active fin F10 overlap eachother.

That is, the FOI structure is formed in the region N where the firstactive fin F10 and the second gate line 352 do not overlap each other,and germanium (Ge) may be included in the oxide film that is formedbelow the first active fin F10 in the region N where the first activefin F10 and the second gate line 352 do not overlap each other.

Further, a fin structure other than the FOI structure is formed in theregion O where the first active fin F10 and the second gate line 352overlap each other, and germanium (Ge) may not be included in the oxidefilm (or other insulating film) that is formed below the second gateline 352 in the region O where the first active fin F10 and the secondgate line 352 overlap each other.

Hereinafter, other parts of the semiconductor device according to theeighth embodiment of the inventive concepts will be described in moredetail with reference to FIGS. 11 to 13.

First, referring to FIG. 11, the semiconductor device according to theeighth embodiment of the inventive concepts may include a pair ofinverters INV1 and INV2 that are connected in parallel between a powersupply node Vcc and a ground node Vss. A first pass transistor PS1 and asecond pass transistor PS2 are connected to the respective output nodesof the inverters INV1 and INV2.

The first pass transistor PS1 and the second pass transistor PS2 may beconnected to a bit line BL and a complementary bit line /BL,respectively. The gates of the first pass transistor PS1 and the secondpass transistor PS2 may be connected to a word line WL.

The first inverter INV1 includes a first pull-up transistor PU1 and afirst pull-down transistor PD1 that are connected in series, and thesecond inverter INV2 includes a second pull-up transistor PU2 and asecond pull-down transistor PD2 that are connected in series.

The first pull-up transistor PU1 and the second pull-up transistor PU2may be PMOS transistors, and the first pull-down transistor PD 1 and thesecond pull-down transistor PD2 may be NMOS transistors.

Further, in order that the first inverter INV1 and the second inverterINV2 constitute one latch circuit, the input node of the first inverterINV1 may be connected to the output node of the second inverter INV2,and the input node of the second inverter INV2 may be connected to theoutput node of the first inverter INV 1.

Referring to FIGS. 11 to 13, the first active fin F10, a second activefin F20, a third active fin F30 and a fourth active fin F40, which arespaced apart from each other, may be formed to extend in a firstdirection (e.g., up-and-down direction of FIG. 12). The second activefin F20 and the third active fin F30 may have lengths that are shorterthan lengths of the first active fin F10 and the fourth active fin F40.

Further, a first gate line 351, the second gate line 352, a third gateline 353 and a fourth gate line 354 are formed to extend in a seconddirection (e.g., left-to-right direction of FIG. 12) to intersect one ormore of the first active fin F 10 to the fourth active fin F40.

Specifically, the first gate line 351 may be formed to completelyintersect the first active fin F10 and the second active fin F20, and toat least partially overlap the end of the third active fin F30. Thethird gate line 353 may be formed to completely intersect the fourthactive fin F40 and the third active fin F30, and to at least partiallyoverlap the end of the second active fin F20. The second gate line 352and the fourth gate line 354 may be formed to intersect the first activefin F10 and the fourth active fin F40, respectively.

As shown in FIG. 12, the first pull-up transistor PU1 is defined at theintersection of the first gate line 351 and the second active fin F20.The first pull-down transistor PD1 is defined at the intersection of thefirst gate line 351 and the first active fin F10. The first passtransistor PS1 is defined at the intersection of the second gate line352 and the first active fin F10.

The second pull-up transistor PU2 is defined at the intersection of thethird gate line 353 and the third active fin F30. The second pull-downtransistor PD2 is defined at the intersection of the third gate line 353and the fourth active fin F40. The second pass transistor PS2 is definedat the intersection of the fourth gate line 354 and the fourth activefin F40.

Although not shown specifically, a recess may be formed on both sides ofeach of the intersections between the first to fourth gate lines 351 to354 and the first to fourth active fins F10 to F40. In the recess, asource/drain may be formed, and a plurality of contacts 361 may beformed.

In addition, a shared contact 362 electrically connects the secondactive fin F20, the third gate line 353 and a wiring 371. A sharedcontact 363 electrically connects the third active fin F30, the firstgate line 351 and a wiring 372.

The first pull-up transistor PU1, the first pull-down transistor PD1,the first pass transistor PS1, the second pull-up transistor PU2, thesecond pull-down transistor PD2 and the second pass transistor PS2 may,for example, be formed as semiconductor devices according to theabove-described embodiments of the inventive concepts.

Hereinafter, a method for fabricating a semiconductor device accordingto some embodiments of the inventive concepts will be described.

FIG. 14 is a flowchart illustrating a method for fabricating asemiconductor device according to an embodiment of the inventiveconcepts. FIG. 15 is a flowchart illustrating a method for fabricating asemiconductor device according to another embodiment of the inventiveconcepts. FIG. 16 is a flowchart illustrating a method for fabricating asemiconductor device according to still another embodiment of theinventive concepts. FIGS. 17 to 22 are diagrams showing intermediatestructures formed in the method for fabricating a semiconductor deviceaccording to one embodiment of the inventive concepts. FIG. 23 is adiagram showing an intermediate structure formed in the method forfabricating a semiconductor device according to another embodiment ofthe inventive concepts. FIGS. 24 to 28 are diagrams showing intermediatestructures formed in the method for fabricating a semiconductor deviceaccording to still another embodiment of the inventive concepts. FIGS.29 and 30 are diagrams showing intermediate structures formed in themethod for fabricating a semiconductor device according to still anotherembodiment of the inventive concepts.

Referring to FIGS. 14 and 17 to 22, in a method for fabricating asemiconductor device according to one embodiment of the inventiveconcepts, a substrate 100 is prepared that includes a fin structureformed thereon (step S100).

Referring to FIG. 17, in order to form a fin structure on the substrate100, a first material layer 101 and a second material layer 102 aresequentially formed on the substrate 100. Then, an etch stop film 150 isformed on the second material layer 102, and a mask film 160 is formedon the etch stop film 150.

Referring to FIG. 18, trenches T1, T2 and T3 may then be formed so thatone or more fin structures are formed that protrude from the substrate100. The trenches T1, T2 and T3 may be formed by using, for example, adry etching process.

In this case, the substrate 100 and the second material layer 102 mayinclude silicon (Si), and the first material layer 101 may includesilicon germanium (SiGe).

Subsequently, an oxide film 110 is formed on the substrate 100 to coverat least a portion of the fin structure (step S110). The oxide film 110may cover the entire side surfaces of the first material layer 101 onthe substrate 100, and may also cover a portion of the second materiallayer 102. FIG. 19 shows a case where the oxide film 110 covers theentire side surfaces of the fin structure, but it will be understoodthat FIG. 19 is an exemplary diagram.

Referring to FIG. 20, the fin structure is then annealed to form a lowerfin LF1 and an upper fin UF1 (step S120). In order to separate the lowerfin LF1 from the upper fin UF1, the first material layer 101 is oxidizedand converted into an oxide film. That is, since the first materiallayer 101 includes silicon germanium (SiGe) and the substrate 100 andthe second material layer 102 include silicon (Si), the first materiallayer 101 is converted into the oxide film that serves as an insulatingfilm earlier than the second material layer 102 due to a difference inoxidation rate between silicon germanium (SiGe) and silicon (Si).

Referring to FIG. 21, subsequently, a portion of the oxide film 110 isremoved. A portion of the upper fin UF1 may be recessed in the uppersurface of the oxide film 110 (step S130).

Then, a gate structure is formed in a direction to intersect the upperfin UF1 (step S140).

Referring to FIG. 22, in some embodiments, the annealing process that isused to form the lower fin LF1 and the upper fin UF1 may include a firstanneal process and a second anneal. The first material layer 101 may beconverted into an oxide film by the first anneal, and the upper surfaceof the lower fin LF1 and the lower surface of the upper fin UF1 may beformed to have a smooth curved surface by the second anneal. Further, aconcentration gradient of germanium (Ge) may be made uniform by thesecond annealing process.

The second annealing process may be performed at a higher temperaturethan the first annealing process. For example, the second annealingprocess may be a laser annealing process.

Referring to FIGS. 15 and 23, a method for fabricating a semiconductordevice according to another embodiment of the inventive concepts furtherincludes, before forming the oxide film 110, recessing the firstmaterial layer 101 included in the fin structure (step S105).

A recess process may be performed to remove a portion of the sidesurface of the first material layer 101. Accordingly, in the subsequentstep, it is possible to increase a speed at which the first materiallayer 101 is converted into the oxide film.

Referring to FIGS. 16 and 24 to 30, a method for fabricating asemiconductor device according to still another embodiment of theinventive concepts further includes, after forming the upper fin UF″(UF″′), forming an epitaxial layer in a region of the upper fin UF″(UF″′) (step S125).

Referring to FIG. 24, when the first material layer 101 is formed on thesubstrate 100, the first material layer 101 may be formed such that theconcentration of silicon germanium (SiGe) is high in a middle portion ofthe first material layer 101 by varying the concentration of silicon(Si) in the silicon germanium (SiGe) layer as a function of height abovethe underlying substrate (i.e., in the direction of the fin structure).As shown in FIG. 24, in such embodiments, after the annealing process isperformed a material layer 30 that is not converted into an oxide filmmay be provided on top of the first material layer 101 that is convertedinto the oxide film by the annealing process. The material layer 30 maycomprise, for example, germanium (Ge). In embodiments where the firstmaterial layer 101 is silicon germanium (SiGe), the middle portion ofthe first material layer 101 may have a silicon concentration such thesilicon germanium (SiGe) layer will quickly oxidize during the anneal inthe oxidizing environment, while the upper portion of the first materiallayer 101 may have a silicon concentration such that the silicongermanium (SiGe) layer will be slow to oxidize during the anneal in theoxidizing environment.

Since the oxidation rate is higher in the middle portion of the silicongermanium (SiGe) layer than in the upper portion of the silicongermanium (SiGe) layer, the fin structure may be separated in the middleportion of the first material layer 101 into upper and lower fins, asshown in FIG. 24 and the upper portion of the first material layer 101may remain as part of the upper fin structure.

Then, referring to FIG. 25, the second material layer 102, the etch stopfilm 150 and the mask film 160 are removed from an upper region of thefin structure, and trenches T4 and T5 are formed.

Referring to FIG. 26, the same material (e.g., germanium (Ge)) as thematerial included in the first material layer 101 is filled in thetrenches T4 and T5 via an epitaxial process, and an upper portion of thematerial filled in the trenches T4 and T5 is removed via a planarizationprocess (see FIG. 27).

Then, referring to FIG. 28, the FOI structure having the upper fin UF1″and the lower fin LF1″ is formed by removing a portion of the oxide film110. In this case, germanium (Ge) is included in the upper fin UF1″.

Referring to FIGS. 29 and 30, in other embodiments, an FOI structurehaving an upper fin UF1″′ and a lower fin LF1″′ may be formed byremoving the material that forms the initial upper fin and then using anepitaxial process to form a second material layer 31, and then forming athird material 32 (e.g., III-V group compound semiconductor material),which is different from the material included in the first materiallayer 101, on the second material 31. As shown in FIG. 30, an upperportion of the oxide film 110 may then be removed. In this case, a III-Vgroup compound semiconductor material is included in the upper fin UF″′.

Hereinafter, an electronic system 500 that includes a semiconductordevice according to some embodiments of the inventive concepts will bedescribed. FIG. 31 is a schematic block diagram of the electronic system500.

Referring to FIG. 31, the electronic system 500 may include a controller510, an interface 520, an input/output (I/O) device 530, a memory device540, a power supply device 550, and a bus 560.

The controller 510, the interface 520, the I/O device 530, the memorydevice 540, and the power supply device 550 may be connected to eachother through the bus 560. The bus 560 corresponds to a path throughwhich data may be transmitted.

The controller 510 may include at least one of a micro-processor, amicro-controller and other logic devices capable of performing similarfunctions to process data.

The interface 520 may serve to transmit/receive data to/from acommunication network. The interface 520 may be a wired or a wirelessinterface. For example, the interface 520 may include an antenna or awired/wireless transceiver or the like.

The I/O device 530 may include a keypad, a display device and the liketo input and output data.

The memory device 540 may store data and/or commands. The semiconductordevices according to some embodiments of the inventive concepts may beincluded as some components of the memory device 540.

The power supply device 550 may convert power that is input from anexternal source and supply the power to each of the components 510 to540.

FIG. 32 is a schematic block diagram for explaining an applicationexample of an electronic system including a semiconductor deviceaccording to some embodiments of the inventive concepts.

Referring to FIG. 32, the electronic system may include a centralprocessing unit (CPU) 610, an interface 620, a peripheral device 630, amain memory device 640, a secondary memory device 650, and a bus 660.

The CPU 610, the interface 620, the peripheral device 630, the mainmemory device 640, and the secondary memory device 650 may be connectedto each other through the bus 660. The bus 660 corresponds to a paththrough which data may be transmitted.

The CPU 610 may include a control device, a computing device or the likethat executes a program and process data.

The interface 620 may transmit/receive data to/from a communicationnetwork. The interface 620 may be a wired or a wireless interface. Forexample, the interface 620 may include an antenna or a wired/wirelesstransceiver or the like.

The peripheral device 630 may include a mouse, a keyboard, a displaydevice, a printer device and the like to input and output data.

The main memory device 640 may transmit/receive data to/from the CPU610, and store data and/or commands and the like required for executingthe program. Semiconductor devices according to embodiments of theinventive concepts may be provided as some components of the main memorydevice 640.

The secondary memory device 650 may include a non-volatile storagedevice such as a magnetic tape, magnetic disk, floppy disk, hard diskand optical disk to store data and/or commands and the like. Thesecondary memory device 650 can store data even when the power supply ofthe electronic system is shut off.

The semiconductor device according to some embodiments of the inventiveconcepts may be provided as one of various components of an electronicapparatus such as a computer, ultra mobile PC (UMPC), workstation,net-book, personal digital assistant (PDA), portable computer, webtablet, wireless phone, mobile phone, smart phone, e-book, portablemultimedia player (PMP), portable game console, navigation device, blackbox, digital camera, 3-dimensional television, digital audio recorder,digital audio player, digital picture recorder, digital picture player,digital video recorder, digital video player, apparatus capable oftransmitting and receiving information in wireless environment, one ofvarious electronic apparatuses constituting a home network, one ofvarious electronic apparatuses constituting a computer network, one ofvarious electronic apparatuses constituting a telematics network, RFIDdevice, and one of various components forming a computing system.

While the inventive concepts have been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the inventive concepts as defined by the following claims. It istherefore desired that the present embodiments be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than the foregoing description to indicatethe scope of the inventive concepts.

What is claimed is:
 1. A semiconductor device comprising: a lower finthat protrudes upwardly from a substrate and that extends in a firstdirection; an oxide film on the lower fin; an upper fin that extends inthe first direction above the lower fin, the upper fin protrudingupwardly from the oxide film and electrically spaced apart from thelower fin; and a gate structure on the upper fin that extends in asecond direction to intersect the upper fin, wherein germanium (Ge) isincluded in a portion of the oxide film that is between the lower finand the upper fin and outside of the upper fin, and wherein the upperfin includes a first material layer that includes a first material and asecond material layer that includes a second material that is differentthan the first material.
 2. The semiconductor device of claim 1, whereinan upper surface of the lower fin has a first, tip portion and a lowersurface of the upper fin has a second tip portion.
 3. The semiconductordevice of claim 1, wherein the second material is germanium (Ge).
 4. Thesemiconductor device of claim 1, wherein the lower fin and the upper fincomprise different materials.
 5. The semiconductor device of claim 4,wherein the upper fin includes a third material layer and a fourthmaterial layer, and the lower fin, the third material layer, and thefourth material layer comprise different materials.
 6. The semiconductordevice of claim 5, wherein the fourth material layer includes a III-Vgroup compound semiconductor material.
 7. The semiconductor device ofclaim 1, wherein a portion of the upper fin is recessed into an uppersurface of the oxide film.
 8. The semiconductor device of claim 1,wherein the upper fin comprises a first epitaxial material layer that isfree of germanium.
 9. The semiconductor device of claim 1, wherein theoxide film is an oxide of silicon germanium (SiGe) that extendssubstantially from the lower fin to the upper fin.
 10. A semiconductordevice, comprising: a first lower fin that extends in a first direction;a second lower fin that extends in the first direction that is spacedapart from the first lower fin; an oxide layer on side surfaces and topsurfaces of the first lower fin and the second lower fin; a first upperfin on the oxide layer, the first upper fin extending in the firstdirection above the first lower fin and spaced apart from the firstlower fin; and a second upper fin on the oxide layer, the second upperfin extending in the first direction above the second lower fin andspaced apart from the second lower fin, wherein the oxide layer includesa first portion that is between the first lower fin and the first uppertin that includes germanium (Ge), a second portion that is between thesecond lower fin and the second upper fin that includes germanium, and athird portion that is between the first portion and the second portionthat does not include germanium, and wherein an upper surface of thefirst lower fin and a bottom surface of the first upper fin aresubstantially parallel to each other.
 11. The semiconductor device ofclaim 10, wherein the first and second portions of the oxide layercomprise oxidized silicon germanium (SiGe).
 12. The semiconductor deviceof claim 10, wherein a width of an upper portion of the first lower finis smaller than a width of a lower portion of the first lower fin, andwherein a width of an upper portion of the second lower fin is smallerthan a width of a lower portion of the second lower fin.
 13. Thesemiconductor device of claim 12, wherein a width of a lower portion ofthe first upper fin is smaller than a width of an upper portion of thefirst upper fin, and wherein a width of a lower portion of the secondupper fin is smaller than a width of an upper portion of the secondupper fin.
 14. The semiconductor device of claim 10, wherein the firstupper fin and the second upper fin each include germanium (Ge).
 15. Thesemiconductor device of claim 10, wherein the first upper fin comprisesan epitaxial layer.
 16. A semiconductor device comprising: a lower finthat protrudes upwardly from a substrate and that extends in a firstdirection; an oxide film on the lower fin; an upper fin that extends inthe first direction above the lower fin, the upper fin protrudingupwardly from the oxide film and electrically spaced apart from thelower fin; and a gate structure on the upper fin that extends in asecond direction to intersect the upper fin, wherein germanium (Ge) isincluded in a portion of the oxide film that is between the lower finand the upper fin, and wherein an upper surface of the lower fin and abottom surface of the upper fin are substantially parallel to eachother.
 17. The semiconductor device of claim 16, wherein the upper fincomprises an epitaxial layer.
 18. The semiconductor device of claim 17,wherein the epitaxial layer comprises silicon germanium.
 19. Thesemiconductor device of claim 17, wherein the epitaxial layer is a firstmaterial layer, and wherein the upper fin further comprises a secondmaterial layer that is free of germanium.
 20. The semiconductor deviceof claim 19, wherein the second material layer comprises a III-V groupcompound semiconductor material.